The present invention is generally drawn to optoelectric emitters and optoelectric detectors. Optoelectric emitters and optoelectric detectors are used for many purposes, including communications (e.g. optical interconnects, on-chip integrated photonic components) in both the civilian world and the military world. Some optoelectric emitters and optoelectric detectors have a small spectrum of operation, whereas others have a relatively broad spectrum of operation. Further, some are tunable over a spectral range. However, conventional optoelectric emitters and optoelectric detectors based on 3D bulk semiconductors are not tunable with sufficient precision to be reliably used for some military purposes. Graphene, mankind's first truly isolated 2D crystal, is a unique and promising material for tunable light-matter interactions due to its gate-variable optical transitions. Its discovery and peculiar properties caused a paradigm shift in material science and naturally led to the search for other 2D monolayer semiconductors called transition metal dichalcogenides (TMDs) and 2D insulators such as hexagonal boron nitride. Several recent publications have demonstrated non-negligible light-emission (e.g. hot electron luminescence) from graphene and hexagonal boron nitride via the quantum tunneling of hot electrons as well as light emission from MoS2 and the Stark Effect bandgap reduction in MoS2, albeit this Stark shift was relative small (e.g. 16 meV) and existed only at cryogenic temperatures (e.g. 10K). Also, a tunable bandgap was realized in bilayer graphene, but is fundamentally limited to <0.3 eV change in bandgap due to its band structure. However, scalable, CMOS-compatible, voltage-tunable wavelength-agile photon emission from these 2D materials at room temperature currently does not exist. The realization of such a unique capability would present an asymmetric advantage to the warfighter because unlike 2D materials, conventional bulk semiconductor materials feature a known, limited, and static spectral range for photoemission and photodetection (e.g. due to the bulk semiconductor materials' fixed bandgaps). By exploiting the widely-tunable direct bandgaps in 2D materials, the warfighter could continuously tune (e.g. in-situ via voltage) the frequency of his or her emitter/detector and thus achieve spectrum dominance over the enemy. That is, the warfighter would be able to communicate/operate in spectral regions where their enemies are unable to since the enemies would be using commercial emitters/detectors based on bulk semiconductors with fixed bandgaps and spectral regions. With our innovative ion-gel 2D-LET device structure, we expect a much larger shift in the direct bandgaps of 2D TMDs such as MoS2, as well as a much larger photon wavelength-agile response from the visible to the mid-infrared spectral regimes at room temperature. This is due to the nanometer thick electric dipole layer that forms in the vicinity of the 2D material's surface via ion-gel gating, which leads to stronger perturbing electric fields and hence an enhanced giant Stark Effect at room temperature.
Accordingly, for at least the foregoing reasons there exists a need for an optoelectronic device that is capable of emitting light over a broad spectral range from the visible to the mid-infrared.